Experimental method and device for measuring heat release rate pulsation by adopting multiple microphones

Abstract

The invention relates to an experimental method and device for measuring heat release rate pulsation by adopting multiple microphones. The experimental method and device are used for research on measurement of combustion instability of an aerospace engine. The sound field pressures before and after a heat source in a combustion chamber are measured based on a multi-microphone method, and heat release rate pulsation of the heat source is obtained through step function derivation at the heat source. The experimental device is composed of multi-microphone pressure measuring systems installed on the upstream and the downstream of a heat source and a sound source installed on the upstream of the heat source. A conventional measurement method is mainly an optical method, and when a heat source is flame, indirect measurement is realized by measuring the concentration of an intermediate product generated by combustion and the method is limited to premixed flame; when the heat source is not flame, no measuring method exists. According to the acoustic measurement method provided by the invention, the heat release rate pulsation is calculated by measuring the pressure fluctuation in the system, so that the acoustic measurement method is suitable for measuring the heat release rates of various heat sources, has the advantages of low cost, simple structure, convenience in adjustment and thelike, and is favorable for researching the measurement of the combustion instability of the aerospace engine.

Description

technical field [0001] The invention relates to an experimental method and device for measuring heat release rate pulsation by using multiple microphones, and is mainly used in the research of combustion instability measurement of aerospace engines. Background technique [0002] During the working process of gas turbines and aerospace engines, the unstable heat release in the combustion chamber and the coupling effect of the acoustic system will cause combustion instability problems. According to the Rayleigh criterion, when the phase difference between the combustion heat release and the pressure of the sound wave is less than 90 degrees, the sound wave continues to gain energy, resulting in severe pressure oscillations. Combustion instability is very harmful, which will cause extremely high combustion rate and heat transfer rate, and bring great challenges to the thermal protection of the combustion chamber wall. The severe pressure oscillation will even cause damage to th...

AI Technical Summary

Problems solved by technology

However, the optical measurement method cannot measure the instantaneous heat release rate pulsation, and can only obtain the average information on the measurement optical path, and lacks sufficient spatial resolution

Optical measurement methods often require an optical measurement window, the measurement optical path is complicated, the device is expensive, and there are extremely high requirements for the experimental environment and the operating ability of the experimenter

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